大地电磁测深法在冀中坳陷深部碳酸盐岩热储调查评价中的应用

Application of the magnetotelluric sounding method in the investigation and evaluation of deep carbonate rock heat storage in the Jizhong Depression

地热资源作为一种清洁能源,在“双碳”背景下,其开发和利用越来越受到重视。为了探查渤海湾盆地的冀中坳陷深部碳酸盐岩的热储条件,笔者等利用3条大地电磁测深剖面,进行了数据处理、分析和反演,获得可靠的二维电阻率模型和电阻率等深度平面图。分析研究区深部电性结构特征及主要断裂构造特征,同时根据基底隆起形成的高阻异常对深部碳酸盐岩分布和埋深进行了推断,并对冀中坳陷深部碳酸盐岩热储进行评价,以圈定地热异常远景区。分析认为:①研究区电性结构可以被划分为5层,其中第5电性层为高阻标志层,对应深部碳酸盐岩基底;②据此圈定了3类深部地热远景区:基岩埋深小于4000 m,如高阳低凸起地热远景区、黑龙口低凸起地热远景区(徐水凹陷)和河间潜山地热远景区(饶阳凹陷),基岩埋深4000~5000 m,如雁翎潜山地热远景区(霸县凹陷),基岩埋深5000~5500 m,如肃宁潜山地热远景区和留路潜山地热远景区;③大地电磁测深方法适用于冀中坳陷深部碳酸盐岩热储远景区的探查。深部热储远景区的圈定,可为后期的地热资源评价和开发利用建立基础。

As a kind of clean energy,geothermal resources have been paid more and more attention to its development and utilization under the background of“double carbon”.In order to explore the thermal storage conditions of the deep carbonate rocks in the Jizhong Depression of the Bohai Bay Basin,this paper uses three magnetotelluric sounding profiles for data processing,analysis,and inversion,and obtains reliable two-dimensional resistivity models and resistivity planes.Combining the gravity,aeromagnetic,seismic,and regional geological data of the study area,the deep electrical structure characteristics and main fault structure characteristics of the study area are analyzed,and the distribution and burial depth of deep carbonate rocks are inferred based on the high-resistivity anomalies formed by the basement uplift and evaluate the deep carbonate rock thermal storage in the Jizhong Depression to delineate the geothermal anomaly prospect areas.The results show that:①The electrical structure of the study area can be divided into 5 layers,of which the fifth electrical layer is a high-resistivity marker layer,corresponding to the deep carbonate rock basement;②Based on this,three types of deep geothermal prospect areas are delineated:carbonate rocks buried depth is less than 4000 m,such as Gaoyang low uplift geothermal prospect area,Heilongkou low uplift geothermal prospect area(Xushui sag)and Hejian buried hill geothermal prospect area(Raoyang sag),carbonate rocks buried 4000~5000 m deep,such as Yanling buried hill geothermal prospect area(Baxian Depression),carbonate rocks buried 5000~5500 m deep,such as Suning buried hill and Liulu buried hill geothermal prospect areas;③The magnetotelluric sounding method is suitable for the exploration of the deep carbonate heat storage prospect in the Jizhong Depression.The delineation of the deep thermal storage prospects can establish a foundation for the evaluation,development,and utilization of geothermal resources in the later period.